A typically-known front sub-frame includes a front part having a sub-crash can attachment part, a tension rod supporting part, and a cross member extending in the vehicle width direction so as to face the tension rod supporting part from the inside in the vehicle width direction.
Examples of such a front sub-frame include a configuration in which a crush can (1e) is supported by a tension rod supporting part (2) as illustrated in Patent Document 1, and a front sub-frame structure including a steering rack (7) disposed below the tension rod supporting part (1a) in addition to a tension rod supporting part (1a) and a cross member (2) as shown in Patent Document 2.
Such a front sub-frame needs to include a sub-crash can in as low a position as possible to lower the position of a load (such as a front collision load) receiving point.
In addition, the steering rack, which is disposed at substantially the same height as the front sub-frame, needs to be disposed below the side member extending to the rear side of the tension rod supporting part to improve the flexibility of assembly from the lower side of a steering rack and to improve the layout with other auxiliary machines such as engines. To satisfy such needs, a known front sub-frame includes a structure in which a front sub-frame is disposed so as to be displaced upward in one side (offset upward) with respect to the position of the sub-crush can. However, in such a structure, the load transmission path from the front to the rear of the front sub-frame is displaced in the vertical direction at the time of, e.g., a front collision.
Thus, even the front sub-frame in which the load transmission path is displaced in the vertical direction as described above needs to have a secured load transmission efficiency to the rear at the time of, e.g., a front collision and have an improved support stiffness of the tension rod and attachment stiffness of the sub-crash can.